Biases in Virial Black Hole Masses: An SDSS Perspective
Biases in Virial Black Hole Masses: An SDSS Perspective
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DOI：
10.1086/587475
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发表时间：
2007-09
期刊：
影响因子：
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通讯作者：
Yue Shen;J. Greene;M. Strauss;G. Richards;D. Schneider
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文献类型：
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作者：
Yue Shen;J. Greene;M. Strauss;G. Richards;D. Schneider
我们使用基于Hβ、Mg II和C IV发射线的维里黑洞质量估计，对斯隆数字巡天第五次数据发布中包含的红移范围为0.1 μ z ~ 4.5的约60，000个类星体进行了黑洞质量的计算。在我们的样本中，三条线的宽度遵循对数正态分布，平均值和色散并不强烈依赖于光度或红移。Mg II和Hβ估算的BH质量彼此一致，但C IV和Mg II估算的BH质量之间存在正偏差，与C IV-Mg II蓝移相关，表明C IV估算值受盘风的影响更严重。如果基本的BH质量分布随质量和爱丁顿比分布在固定的真实BH质量具有非零宽度，我们表明，测量的维里BH质量和爱丁顿比分布在有限的光度箱受到Malmquist偏差。我们提出了一个模型，它再现了观测到的维里质量分布，类星体光度函数和线宽分布，它有一个基本的BH质量分布dN/dlog M M−2.6和一个对数正态真爱丁顿比分布在固定的真质量与色散0.4 dex和平均值依赖于BH质量。在这个模型中，观测到的SDSS样本的维里质量（爱丁顿比）分布在有限的光度区间内偏高（低）约0.6 dex。最后，我们比较了射电和宽吸收线类星体与普通类星体在红移和光度上匹配的维里BH质量。
We compile black hole (BH) masses for ~60,000 quasars in the redshift range 0.1≲ z≲ 4.5 included in the Fifth Data Release of the Sloan Digital Sky Survey, using virial BH mass estimators based on the Hβ, Mg II, and C IV emission lines. Within our sample, the widths of the three lines follow lognormal distributions, with means and dispersions that do not depend strongly on luminosity or redshift. The Mg II- and Hβ-estimated BH masses are consistent with one another, but there is a positive bias between the C IV- and Mg II-estimated BH masses correlated with the C IV-Mg II blueshift, suggesting that the C IV estimator is more severely affected by a disk wind. If the underlying BH mass distribution decreases with mass and the Eddington ratio distribution at fixed true BH mass has nonzero width, we show that the measured virial BH mass and Eddington ratio distributions within finite luminosity bins are subject to Malmquist bias. We present a model that reproduces the observed virial mass distribution, quasar luminosity function, and line width distribution of our sample; it has an underlying BH mass distribution dN/dlog M ∝ M−2.6 and a lognormal true Eddington ratio distribution at fixed true mass with dispersion 0.4 dex and mean dependent on BH mass. In this model, the observed virial mass (Eddington ratio) distribution for the SDSS sample is biased high (low) by ~0.6 dex within finite luminosity bins. Finally, we compare virial BH masses of radio and broad absorption line quasars with ordinary quasars matched in redshift and luminosity.